ive broke all kinds of stuff in my rear end this however was just wear and tear probably.... i dont abuse my car or have i been to the track or anything just something thats happend, im listening for any noises for a low fluid sign, nothing yet i think it will be fine till next week but its getting fixed then.
The 8.8 rear used a crush spacer to set pinion bearing preload. The correct way to replace a pinon seal is to replace the crush sleeve too. You have to torque the pinion nut down to several hundred foot pounds and measure preaload, then keep torqing the pinion nut down till you reach the preload spec, too far and you get to do it all over again with a new crush sleeve.
I doubt you got the tools to do it. This might be a case of letting the dealer do it is a good idea.
Or you can replace the crush sleeve with a solid spacer and shims.